The embodiment relates to an electromagnetic switching device. In more particular, the embodiment relates to an electromagnetic switching device capable of improving the endurance by improving the structure of an actuating part.
An electromagnetic switching device is an electric switch device serving as a connection converter to switch on/off a main circuit according to tiny variation of an input current. In the electromagnetic switching device, a contact point is moved by electromagnetic force so that the current is applied or shut off.
FIG. 1 is a sectional view showing a portion of an electromagnetic switching device according to the related art.
A fixed core 5 and a movable core 7, which have hollow structures, are vertically provided in a yoke 4 while being spaced apart from each other, and are pressed in opposition directions to each other by a return spring 8 interposed between the fixed core 5 and the movable core 7.
A shaft 6 is inserted into the centers of the fixed core 5 and the movable core 7. In this case, the shaft 6 is coupled with the movable core 7 by welding a lower end of the shaft 6 with a lower end of the movable core 7. The welded part between the shaft 6 and the movable core 7 is marked in FIG. 1.
In addition, a coil 9 is wound around outer portions of the fixed core 240 and the movable core 7.
Meanwhile, a movable contact point 2 is coupled near an upper end of the shaft 6 above the yoke 210. In addition, a fixed contact point 1 is placed above the movable contact point 2 while being spaced apart from the movable contact point 2.
In addition, the movable contact point 2 is pressed upward by the wipe spring 3, so that the movable contact point 2 may make contact with the fixed contact point 1 at a predetermined pressure.
If a current is applied to the coil 9 under the above structure, the movable core 7 moves upward, so that the shaft 6 coupled with the movable core 7 moves upward. Accordingly, the movable contact point 2 coupled with the shaft 6 makes contact with the fixed contact point 1.
The ascending of the shaft 6 is primarily restricted through the contact between the movable contact point 2 and the fixed contact point 1. However, the ascending force applied to the movable core 7 still remains at the moment in which the movable contact point 2 makes contact with the fixed point 1. A portion of the ascending force is absorbed by the return spring 8, and, finally, the ascending of the shaft 6 and the movable core 7 is terminated due to the collision of the fixed core 5 and the movable core 7.
In this process, the repulse force by the return spring 8 and the impact caused by the collision of the fixed core 5 and the movable core 7 are applied to the welded part between the movable core 7 and the shaft 6.
If the above process is continuously repeated, the welded part may be damaged more rapidly than an expected lifespan.